Using Acoustic Travel Time to Monitor the Heat Variability of Glacial Fjords

2021 ◽  
Author(s):  
Robert Sanchez ◽  
Fiamma Straneo ◽  
Magdalena Andres
Keyword(s):  
Travel Time ◽  
Heat Content ◽  
Temperature Conductivity ◽  
Fjord Circulation ◽  
Oceanic Forcing ◽  
Time Record ◽  
Temperature Records ◽  
Acoustic Travel Time ◽  
The Relationship ◽  
Inflowing Water

AbstractMonitoring the heat content variability of glacial fjords is crucial to understanding the effects of oceanic forcing on marine-terminating glaciers. A Pressure-sensor equipped Inverted Echo Sounder (PIES) was deployed mid-fjord in Sermilik Fjord in southeast Greenland from August 2011 to September 2012 alongside a moored array of instruments recording temperature, conductivity and velocity. Historical hydrography is used to quantify the relationship between acoustic travel time and the vertically-averaged heat content, and a new method is developed for filtering acoustic return echoes in an ice-influenced environment. We show that PIES measurements, combined with a knowledge of the fjord’s two-layer density structure, can be used to reconstruct the thickness and temperature of the inflowing water. Additionally, we find that fjord-shelf exchange events are identifiable in the travel time record implying the PIES can be used to monitor fjord circulation. Finally, we show that PIES data can be combined with moored temperature records to derive the heat content of the upper layer of the fjord where moored instruments are at great risk of being damaged by transiting icebergs.

scholarly journals A Choice Too Far: Transit Difficulty and Early High School Transfer

2020 ◽  
pp. 0013189X2094950 ◽  
Author(s):  
Marc L. Stein ◽  
Julia Burdick-Will ◽  
Jeffrey Grigg
Keyword(s):  
High School ◽  
Travel Time ◽  
Administrative Data ◽  
Public Transportation ◽  
School System ◽  
Ninth Grade ◽  
Public School System ◽  
Baltimore City ◽  
School Transfer ◽  
The Relationship

The challenge of a long and difficult commute to school each day is likely to wear on students, leading some to change schools. We used administrative data from approximately 3,900 students in the Baltimore City Public School System in 2014–2015 to estimate the relationship between travel time on public transportation and school transfer during the ninth grade. We show that students who have relatively more difficult commutes are more likely to transfer than peers in the same school with less difficult commutes. Moreover, we found that when these students change schools, their newly enrolled school is substantially closer to home, requires fewer vehicle transfers, and is less likely to have been included among their initial set of school choices.

Three-Dimensional Acoustic Travel-Time Tomography of the Atmosphere

2008 ◽  
Vol 94 (3) ◽  
pp. 349-358 ◽  
Author(s):  
Sergey N. Vecherin ◽  
Vladimir E. Ostashev ◽  
Keith D. Wilson
Keyword(s):  
Travel Time ◽  
Three Dimensional ◽  
Travel Time Tomography ◽  
Acoustic Travel Time

scholarly journals On the Relationship between Regional Ocean Heat Content and Sea Surface Height

2017 ◽  
Vol 30 (22) ◽  
pp. 9195-9211 ◽  
Author(s):  
John T. Fasullo ◽  
Peter R. Gent
Keyword(s):  
Time Scales ◽  
Low Frequency ◽  
Heat Content ◽  
Sea Surface Height ◽  
Ocean Heat Content ◽  
Ocean Dynamics ◽  
Sea Surface ◽  
Altimeter Data ◽  
Model Control ◽  
The Relationship

Abstract An accurate diagnosis of ocean heat content (OHC) is essential for interpreting climate variability and change, as evidenced for example by the broad range of hypotheses that exists for explaining the recent hiatus in global mean surface warming. Potential insights are explored here by examining relationships between OHC and sea surface height (SSH) in observations and two recently available large ensembles of climate model simulations from the mid-twentieth century to 2100. It is found that in decadal-length observations and a model control simulation with constant forcing, strong ties between OHC and SSH exist, with little temporal or spatial complexity. Agreement is particularly strong on monthly to interannual time scales. In contrast, in forced transient warming simulations, important dependencies in the relationship exist as a function of region and time scale. Near Antarctica, low-frequency SSH variability is driven mainly by changes in the circumpolar current associated with intensified surface winds, leading to correlations between OHC and SSH that are weak and sometimes negative. In subtropical regions, and near other coastal boundaries, negative correlations are also evident on long time scales and are associated with the accumulated effects of changes in the water cycle and ocean dynamics that underlie complexity in the OHC relationship to SSH. Low-frequency variability in observations is found to exhibit similar negative correlations. Combined with altimeter data, these results provide evidence that SSH increases in the Indian and western Pacific Oceans during the hiatus are suggestive of substantial OHC increases. Methods for developing the applicability of altimetry as a constraint on OHC more generally are also discussed.

scholarly journals Prescribed Burning as A Management Tool to Destroy Dry Seeds of Invasive Conifers in Heathland in Denmark

Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 432
Author(s):  
Christian Andreasen ◽  
Kasper Rossing ◽  
Christian Ritz
Keyword(s):  
High Temperature ◽  
Prescribed Burning ◽  
Germination Rate ◽  
Management Tool ◽  
Fuel Load ◽  
The Mean ◽  
Temperature Records ◽  
Conifer Trees ◽  
The Relationship ◽  
Practical Constraints

Non-indigenous conifers are considered invasive to the coastal dune heathland in Denmark, and massive clearing is carried out in an attempt to recreate and keep the original heathland. Burning is a common method for managing, but its feasibility to control the seed bank of conifers has not been investigated. This project shows that the burning of logged conifer trees will often eliminate seeds of lodgepole pine, mugo pine and Sitka spruce, even when the seeds were placed into a depth of five centimeters in the soil. The effect on seeds depends on the fuel load and the fire conditions (e.g., dryness, wind, and temperature). If the seeds were exposed to a high temperature, the seeds were not able to germinate afterward. The temperature was about 80 °C for all species. If the sum of temperatures based on temperature records every 30 s exceeded between 12,000 and 14,000 °C no seeds were able to germinate. The relationship between the mean temperature of the burns and the germination rate at seeds placed in various soil depths was modelled. Findings should be interpreted cautiously as each depth-species combinations were not replicated in space or time due to practical constraints.

A facile route to well-defined imidazolium-based poly(ionic liquid)s of enhanced conductivity via RAFT

2017 ◽  
Vol 8 (35) ◽  
pp. 5433-5443 ◽  
Author(s):  
Paulina Maksym ◽  
Magdalena Tarnacka ◽  
Andrzej Dzienia ◽  
Karol Erfurt ◽  
Anna Chrobok ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Conductivity ◽  
Poly Ionic Liquid ◽  
The Relationship ◽  
Enhanced Conductivity ◽  
Facile Route

Examining the relationship between the glass transition temperature, conductivity and molecular weight of tailored imidazolium-based PILs synthesized via RAFT.

Acoustic travel time and intensity fluctuations measured in the SWARM95 experiment

1997 ◽  
Vol 101 (5) ◽  
pp. 3016-3016 ◽  
Author(s):  
Robert H. Headrick ◽  
James F. Lynch ◽  
Marshall Orr ◽  
Bruce Pasewark ◽  
Steve Wolf ◽  
...  
Keyword(s):  
Travel Time ◽  
Intensity Fluctuations ◽  
Acoustic Travel Time

Relationship between body heat content and finger temperature during cold exposure

2001 ◽  
Vol 90 (6) ◽  
pp. 2445-2452 ◽  
Author(s):  
Dragan Brajkovic ◽  
Michel B. Ducharme ◽  
John Frim
Keyword(s):  
Skin Temperature ◽  
Heat Storage ◽  
Heat Content ◽  
The Body ◽  
Finger Temperature ◽  
Finger Dexterity ◽  
The Relationship ◽  
Finger Skin ◽  
Body Heat ◽  
Partitional Calorimetry

The purpose of the present experiment was to examine the relationship between rate of body heat storage (S˙), change in body heat content (ΔHb), extremity temperatures, and finger dexterity. S˙, ΔHb , finger skin temperature (Tfing), toe skin temperature, finger dexterity, and rectal temperature were measured during active torso heating while the subjects sat in a chair and were exposed to −25°C air. S˙ and ΔHb were measured using partitional calorimetry, rather than thermometry, which was used in the majority of previous studies. Eight men were exposed to four conditions in which the clothing covering the body or the level of torso heating was modified. After 3 h, Tfing was 34.9 ± 0.4, 31.2 ± 1.2, 18.3 ± 3.1, and 12.1 ± 0.5°C for the four conditions, whereas finger dexterity decreased by 0, 0, 26, and 39%, respectively. In contrast to some past studies, extremity comfort can be maintained, despite S˙ that is slightly negative. This study also found a direct linear relationship between ΔHb and Tfing and toe skin temperature at a negative ΔHb. In addition, ΔHb was a better indicator of the relative changes in extremity temperatures and finger dexterity over time than S˙.

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